Ive been shooting the CT 140 gr BST out of my 700 7mm for a while and have had good accuracy but i cant seem to get the velocity i should be seeing.

my load is 140 gr with 65 gr H4831SC seated at the rifling(3.380") and im getting 2890 fps when i should be over 3100.

the only thing i can figure is the Lubalox coating that is supposed to reduce friction doesnt let the round reach sufficient pressures to get the same velocity as a copper jacketed bullet.

anyone else have this problem?

With a 24" barrel your load calculates 2911 in QL so I would call it right on.

Not sure where you are pulling data. The norm AOL of the 7mag is 3.29 I believe if you seat the bullet out to 3.38 your are increasing your case size and lowering your pressure. Probably in the 50fps range. Nothing wrong with that it will jsut take a little more powder.

But it is normal to see velocties 150' different between twin rifles. So comparing to a load manual can be off even more.

how did u calculate 2911?

my hornady book lists 139 gr with 63.5 gr of H4831 (max load) @ 3100 fps.

im just wondering why im getting 2890 with more than a max load, it defeats the purpose of having a magnum rifle at that velocity.

quote:

Originally posted by gilk:
how did u calculate 2911?

my hornady book lists 139 gr with 63.5 gr of H4831 (max load) @ 3100 fps.

im just wondering why im getting 2890 with more than a max load, it defeats the purpose of having a magnum rifle at that velocity.

He used Quick Load (QL) a computer program that calculates performance based on the particular load data of the cartridge.

quote:

my hornady book lists 139 gr with 63.5 gr of H4831 (max load) @ 3100 fps

Yep QL. Even the Hodgdon site calls that load around 55,000 I believe. My Hornady book before lawyers (vol11) Calls max with the 139 as 71.4 in the red(near max foot note) and 69.8 in the white.

In the what its worth QL using the 3.29 calls 69.8grs as right at 61,000 the 71.4 at 65,400.

In my 7mag 63.5 was a real light load. Like you I seated a touch longer and was just under 70gr(from memory)with 140 BT for just over 3200.

ok, my hornady 3rd edition book list 66.7 as max.

i think I'll try 69 tomorrow, do you think that is a safe load?

where can i get a free copy of QL?

quote:

i think I'll try 69 tomorrow, do you think that is a safe load?

where can i get a free copy of QL?

A free copy of QL doesn't exist. It will run you $150.
http://www.neconos.com/category/Software-2

No way would I say jump from 63.5 to 69. I would have no trouble working up from 63.5 to 69. It will depend on your chamber, barrel and burn speed of you specific can of 4831.

Sounds like a change in powder would be a good move.....or a 280 Ackley!!

http://www.nosler.com/Reloadin...gnum-140-Grains.aspx

http://www.nosler.com/Reloadin...oved-140-Grains.aspx

quote:

Originally posted by wrongtarget:
Sounds like a change in powder would be a good move.....or a 280 Ackley!!

http://www.nosler.com/Reloadin...gnum-140-Grains.aspx

http://www.nosler.com/Reloadin...oved-140-Grains.aspx

Yup...IMR-4895 looks good to me.

quote:

Yup...IMR-4895 looks good to me.

Too fast for me.

Let's see Nosler calls max for the 280AI which is 11% smaller capacity 62.5grs which is only 1 grain less than the Hornady book for the 7mag?

Nothing really wrong with 4831 in the 7mag just needs more of it. Heck I ran more than 63.5 in my 280PDK which is the size of a 7mm Gibbs. If it was mine I look to 7828, RL22 and MRP. But I do lean towards the double based powders.

The Nosler #4 calls max load for the 140gr as 66gr of IMR 4831 which is normally 2-4 grs hotter than H4831.